The present invention relates generally to a process and apparatus for producing colored images and patterns by solid application of only two coloring media to elicit the appearance of four colors. Application of this patent may be illustrated by a printing process.
The most common method of printing is the use of a single-color press and a white substrate. The printed sheet exhibits two colors, white and the color of the ink used. The half-tone process permits printing all shades of color between white and the color of a solid printing of the ink. A common example of half-tone printing is a so-called “black and white” picture in a newspaper.
Full-color printing, by overprinting yellow, magenta, cyan, and black half-tone images on a white substrate, can exhibit any color within a broad gamut. Some printing devices in common use employ six inks to obtain a larger gamut than could be achieved with four colored inks.